diff options
Diffstat (limited to 'include/qemu/compiler.h')
| -rw-r--r-- | include/qemu/compiler.h | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 496dac5..1c2b673 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -182,19 +182,6 @@ #define QEMU_DISABLE_CFI #endif -/* - * Apple clang version 14 has a bug in its __builtin_subcll(); define - * BUILTIN_SUBCLL_BROKEN for the offending versions so we can avoid it. - * When a version of Apple clang which has this bug fixed is released - * we can add an upper bound to this check. - * See https://gitlab.com/qemu-project/qemu/-/issues/1631 - * and https://gitlab.com/qemu-project/qemu/-/issues/1659 for details. - * The bug never made it into any upstream LLVM releases, only Apple ones. - */ -#if defined(__apple_build_version__) && __clang_major__ >= 14 -#define BUILTIN_SUBCLL_BROKEN -#endif - #if __has_attribute(annotate) #define QEMU_ANNOTATE(x) __attribute__((annotate(x))) #else @@ -208,6 +195,26 @@ #endif /* + * Disable -ftrivial-auto-var-init on a local variable. + * + * Use this in cases where there a method in the device I/O path (or other + * important hot paths), that has large variables on the stack. A rule of + * thumb is that "large" means a method with 4kb data in the local stack + * frame. Any variables which are KB in size, should be annotated with this + * attribute, to pre-emptively eliminate any potential overhead from the + * compiler's implicit zero'ing of memory. + * + * Given that this turns off a security hardening feature, when using this + * to flag variables, it is important that the code is double-checked to + * ensure there is no possible use of uninitialized data in the method. + */ +#if __has_attribute(uninitialized) +# define QEMU_UNINITIALIZED __attribute__((uninitialized)) +#else +# define QEMU_UNINITIALIZED +#endif + +/* * http://clang.llvm.org/docs/ThreadSafetyAnalysis.html * * TSA is available since clang 3.6-ish. |